The term Greater Serbia or Great Serbia () describes the Serbian nationalist and irredentist ideology of the creation of a Serb state which would incorporate all regions of traditional significance to Serbs, a South Slavic ethnic group, including regions outside modern-day Serbia that are partly populated by Serbs. The initial movement's main ideology (Pan-Serbism) was to unite all Serbs (or all territory historically ruled, seen to be populated by, or perceived to be belonging to Serbs) into one state, claiming, depending on the version, different areas of many surrounding countries, regardless of non-Serb populations present.

The Greater Serbian ideology includes claims to various territories aside from modern-day Serbia, including the whole of the former Yugoslavia except Slovenia and part of Croatia. According to Jozo Tomasevich, in some historical forms, Greater Serbian aspirations also included parts of Albania, Bulgaria, Hungary and Romania. Its inspiration comes from the medieval Serbian Empire which existed briefly in 14th-century Southeast Europe from 1346 to 1371, prior to the Ottoman conquest of the Balkans. Some territories intended to be incorporated in the Greater Serbia exceeded the boundaries of the Serbian Empire, however.

Historical overview

Following the growing nationalistic tendency in Europe from the 18th century onwards (as exemplified in the unification of Italy), Serbs in Serbia – after first achieving the recognition of the Principality of Serbia within the Ottoman Empire in 1817 – experienced a popular desire for full unification with the Serbs of the remaining territories, mainly those living in neighbouring entities. However, as stated by Christopher Clark, the "underpinning the idea of the 'unification of all Serbs' was a mental image of Serbia that bore little relation to the political map of the Balkans at the turn of the twentieth century", and the "historical template" for the Serbian state was the restoration of the Serbian Empire during the time of Stefan Dušan (1346–1355). Although the empire was short-lived, multi-ethnic and did not include some territories (e.g. Bosnia), the restoration was perceived as a "historical right" compatible with creating a monoethnic nation-state, as the "Serb patriots saw no inconsistency here, since they argued that virtually all the inhabitants of these lands were essentially Serbs". These aspirations were also reproduced in books and maps, for example by Dimitrije Davidović (1821 and 1846), Miloš Milojević (1877), Spiridon Gopčević (1889), Vladan Đorđević (1902), but also in Europe by Apollon Aleksandrovich Maykov (1857), Henri Thiers (1862), Alexander Pypin and Włodzimierz Spasowicz (1879), Ernest Denis (1915), due to the Serbian diplomatic propaganda.

The Serbian Minister of Internal Affairs, Ilija Garašanin, a conservative statesman with Bismarckian aspirations, formulated the idea of Serbian territorial expansion in 1844 in Načertanije (), a secret draft political programme. According to the draft, the new Serbian state could include the neighboring areas of Montenegro, Northern Albania, Bosnia and Herzegovina. In the early-20th century, all political parties of the Kingdom of Serbia (except for the Social Democratic Party) planned to form a Balkan Federation, and generally accepted the idea of uniting all Serbs into one only Serbian state which would be a part of that proposed Balkan Federation. From the formation of the Principality until the First World War of 1914-1918, the Serbian state successively expanded its territory.

After the end of the Balkan Wars in 1913, the Kingdom of Serbia expanded towards the south, but there was a mixed reaction to the events, because promises of lands giving access to the Adriatic Sea remained unfulfilled. Instead, Serbia received the territories of Vardar Macedonia (coveted by the Kingdom of Bulgaria) and the Serbian Army had to evacuate the coastal territories that would become part of the newly-formed Principality of Albania. This settlement, together with the Austro-Hungarian annexation of Bosnia in 1908, frustrated Serbian aspirations: a large number of Serbs remained outside of the Serbian kingdom.

After World War I, a new unified state called the Kingdom of Serbs, Croats and Slovenes formed, which included the Kingdom of Serbia, the short-lived State of Slovenes, Croats and Serbs and some territories from the disintegrated Austro-Hungarian monarchy. Ruled by the Serbian royal family, the House of Karađorđević, it would be renamed as the Kingdom of Yugoslavia in 1929. During the inter-war period (1918 to 1939), many Serb-oriented political parties promoted the concept of a strong centralised country with the doctine of Yugoslavism, while their opponents favored decentralization and demanded autonomy for the regions.

Following the German-led invasion of Yugoslavia in 1941, tensions grew and erupted into one of the most brutal civil wars that occurred in World War II. The Royal Government soon capitulated and fled to exile in London. The Chetniks, who advocated the restoration of the monarchy, initially resisted the invaders, but would eventually collaborate with the Axis powers with the goal of forming a post-war Greater Serbia. On the other hand, the Partisans, a multi-ethnic antifascist movement, waged an ongoing guerrilla campaign against the occupying forces and supported the transformation of the old royal Yugoslavia into a socialist federal republic. The Serbs were largely divided between these two factions, leading to internal fighting. Others found themselves in the collaborationist factions of Milan Nedić and Dimitrije Ljotić such as the Serbian Volunteer Corps. Beside this, other Yugoslav non-Serb nationalists took advantage of the situation and allied themselves with the Axis powers, regarding this moment as their historical opportunity of fulfilling their own irredentist aspirations, which they saw as a better alternative to the Serbian-led rule of the interwar period.

History Obradović's Pan-Serbism

The first person to formulate the modern idea of Pan-Serbism was Dositej Obradović (1739–1811), a writer and thinker who dedicated his writings to the "Slavoserbian people", which he described as "the inhabitants of Serbia, Bosnia, Herzegovina, Montenegro, Dalmatia, Croatia, Syrmium, Banat, and Bačka", and who he regarded as all his "Serbian brethren, regardless of their church and religion". Other proponents of Pan-Serbism included historian Jovan Rajić and politician and lawyer Sava Tekelija, both of whom published works incorporating many of the aforementioned areas under a single umbrella name of "Serbian lands". The concept of Pan-Serbism espoused by these three was not an imperialist one, based upon the notion of Serbian conquest, but a rationalist one. They all believed that rationalism would overcome the barriers of religion that separated the Slavs into Orthodox Christians, Catholics, and Muslims, uniting the peoples as one nation. The idea of a unification and homogenization by force was propounded by Petar II Petrović-Njegoš (1813–1851).

Stratimirović's Serbia Rediviva and Tekelija's Illyria Stefan Stratimirović, the Serbian Metropolitan in Sremski Karlovci from 1790 to 1836 and the head of the Serbian Church in the Habsburg monarchy, was one of the Serbs who fought for independence, and unification. His most significant and influential political work is the Memorandum, written in June 1804. The core idea from the Memorandum stipulated that all Serbs should live in a single national state. This renewed Serbian national state (which may be called Serbia rediviva) was based on the idea that all Serbs, both those from Turkey (the Ottoman Empire) and those from Austria, should be united within it. Consequently, he proposed that the following territories of Austria inhabited by Serbs should be included which Stratimirović himself called the Slavonic-Serbian State (Slavenoserbsko gosudarstvo): the Bay of Kotor with the town of Kotor, the parts of Dalmatia and Croatia east of the Una River, the Krka River, and the city of Šibenik, the territory between the Danube River, the Sava River, and the Vuka River and its surroundings, and the greater part of Slavonia.

Serbia rediviva would also consist, according to his view, of the following historical-ethnic Serbian lands which at that time belonged to the Ottoman Empire: the Belgrade Pashalik (from the Sava and Danube rivers in the north to the West Morava River in the south, and from the Drina River in the west to the Timok River in the east); Bosnia and Herzegovina, Montenegro, Kosovo and Metohija, and the northwestern part of present-day Bulgaria with the town of Vidin, its surrounding area, and the Lom River. He also mentioned the part of western Wallachia between the Danube and Jiu rivers, present-day southeastern Serbia with the towns of Niš, Leskovac, Vranje, and Bujanovac, and the northern part of present-day Albania with the town of Shkodra which should be considered part of the "ethnic space" of the Serbian people.

In determining the borders of the renewed Serbia, he applied both the historical and the ethnic principle. According to the first principle, the territories of medieval Serbia and Duklja (Montenegro) would constitute part of it. According to the second principle, all Balkan territories inhabited by ethnic Serbs—that is, according to Stratimirović’s understanding, the entire Orthodox population of the South Slavs whose mother tongue was the Shtokavian dialect and whose literary language was Slavonic-Serbian—would also be included in this state. Regarding the determination of the ethnic space of the Serbian people, the Metropolitan of Karlovci was strongly influenced by the theory of the ethnic-linguistic criterion for defining the Serbian nation, which at that time was favored by the Serbian nobleman from Arad and president of the Matica srpska, Sava Tekelija. Tekelija’s ethnic-linguistic concept of “Serbdom” was elaborated in his short essay titled Description of Life (Opisanije života).

Tekelija believed that all members of the South Slavs who used the Shtokavian, Kajkavian, or Chakavian dialect, regardless of their religious affiliation, belonged to the true Serbian people. Thus, according to his understanding, the following South Slavic lands were inhabited by ethnic-linguistic Serbs: Serbia in the narrower sense (minus Vojvodina), Kosovo, Bosnia and Herzegovina, Bulgaria, Montenegro, North Macedonia, the Republic of Ragusa, Carniola, Styria, Carinthia, Southern Hungary (present-day Vojvodina), and Northern Albania. Tekelija advocated that all the above-mentioned South Slavic territories, inhabited by these "Serbs", should form a single unified Serbian national state, whose borders would extend from the Black Sea to the Alps, and from the Adriatic Sea to north of the Danube. This united Serbia would be inhabited by a majority Orthodox population and a minority Roman Catholic and Muslim population. Tekelija called all the above-mentioned "Serbian", i.e. South Slavic, lands by the common name Illyria (Illyricum), being strongly influenced by the widely spread theory dating back to the Middle Ages that all South Slavs were of Old-Balkan Illyrian origin, who, in Tekelija’s view, were ethnic-linguistic Serbs. Stratimirović did not fully adopt Tekelija’s linguistic conception as he believed that only the Orthodox believers of the South Slavic population who used the Shtokavian dialect as their spoken language and Slavonic-Serbian as their literary language were, in essence, true ethnic Serbs. Thus, Stratimirović’s concept of defining Serbdom can be described as a religious-linguistic one.

Slaveno–Serb Empire of Petar I Petrović